Do not set func word to be handle!

There doesn't seem to be a reason to do this (any more?). Just call
Init_Word and GC will be happy.

This removes an additional static word for error reporting.
Support wrapping c functions with varargs

As the number of function arguments can't be infered from either C
function or rebol script, it requires a block on rebol side to call the
routine.

The vararg is denoted by a "...", same as in "C":

libc: make library! %libc.so.6
printf: make routine! [
	[
		fmt [pointer]
		...
		return: [int32]
	]
	libc "printf"
]

printf compose [
	"hello %s%c"
	"world" [pointer]
	(to integer! newline) [int8]
]
Clear memory from Make_Node

or garbage could be there
Add a testing file for wrapping variadic functions
Use precalculated n_fixed
Check Atoms before using them

such that it runs with xwayland in weston